The present invention refers to an espresso brewing head unit comprising a potshaped coffee receptacle in which a filter plate with coffee discharge openings is provided, a lateral wall of the coffee receptacle and the filter plate defining the filling volume of the coffee receptacle.
Such an espresso brewing head unit is known from DE 197 11 025 C1. This espresso brewing head unit comprises a potshaped coffee receptacle which consists essentially of plastic material, a reinforcing metal ring being formed in the upper rim of said coffee receptacle. Laterally projecting locking flanges are also reinforced with metal and serve as components of a bayonet lock for attaching the unit to an espresso machine. A filter plate is inserted in the coffee receptacle. This can be a simple filter plate which is anchored in the wall of the coffee receptacle or which is inserted in said coffee receptacle in a separate, framelike injection moulded part. It is also possible to arrange below the filter plate a support plate having a central discharge opening. At the bottom of the coffee receptacle there is a closure cap provided with one or with a plurality of coffee discharge openings. The filter plate extends at right angles to the axis of the coffee receptacle which is provided with a laterally arranged handle.
Although this structural design constitutes a very compact espresso brewing head unit that can be produced at a reasonable price, the filling volume located above the filter plate and surrounded by the wall of the coffee receptacle is predetermined so that it is always only a specific amount of espresso which can be produced at a time or that in the case of fractional filling (e.g. half filling) a deterioration in the quality of the espresso made must be reckoned with.
For a good quality of the espresso, it is important that a dense coffee cake through which the hot water must flow is formed in the coffee receptacle.
Hence, it is the object of the present invention to provide a compact espresso brewing head unit which produces good quality independently of the amount of espresso to be made.